1. Field of Invention
This invention relates to devices for aiding amateur gardeners in germinating plant seeds, producing and growing seedlings for the home garden; specifically to a system which protects germination of seeds and growth of seedlings within biodegradable pods which may be introduced into a natural environment without transplantation.
2. Description of Prior Art
Most of the more than 80 million Americans who garden do not plant seeds directly into the soil. Excessive cold or heat, herbivorous insects and birds, all may prevent successful seed germination and seedling growth. As a result, many gardeners plant seeds in separate containers and then transplant them to the garden when conditions become more hospitable. Others purchase commercially grown seedlings for transplantation. Still, most homegrown vegetables and many flowers are produced from seeds.
Even for experienced gardeners, the germination of seeds in containers and their timely transplantation into the soil is a challenging task. Sixty percent of those Americans who garden do so only on a very limited basis. Inexperience, lack of time, and the difficulties of growing and transplanting seedlings leads to frequent failures, waste, frustration, and unnecessary expense.
The method currently used by most gardeners requires carefully selecting and properly assembling the necessary elements. These elements must then be monitored closely to minimize losses during germination and early development of seedlings. Additional losses at the time of transplantation into a natural environment are common.
The usual process for producing plants from seeds is to begin by obtaining potting soil. To this, the gardener may add milled sphagnum moss, perlite, sand and/or vermiculite. Proper proportions of these ingredients are placed in containers with drain holes. Large numbers of seeds are purchased in packages, with one or more seeds planted in each container at a specified depth. The gardener then estimates the proper amount of water to add to establish proper soil moisture content for germination.
A hundred plants or more may be required for a modest garden. Once seeds are planted, the gardener must rely on personal experience and knowledge to determine when to add water and to estimate how much water should be added to maintain the desired level of soil moisture. The gardener must monitor and control lighting and temperature, often by moving individual containers to achieve optimum conditions. When seedlings form true leaves, the gardener transplants them into larger containers or into the garden.
Transplantation is traumatic to plants. Any sudden change in environment can cause a slowing or stunting of growth from which the plant may never recover. For some varieties of plants, 80 or 90 percent of seeds cannot be will fail to survive germination and transplantation by an average gardener.
As a result, some amateur gardeners purchase bedding plants grown in nurseries or greenhouses for transplantation. In such cases, it may be necessary to engage in a regime of hardening off to acclimate plants gradually to the harsher conditions found in the garden. To minimize losses the gardener must monitor temperature, wind, lighting conditions and other factors and promptly move the plants once or more each day for up to a week or more prior to transplantation. Commercially grown seedlings, or bedding plants, also may become rootbound in their containers, increasing the likelihood of plant loss.
Gardeners have long sought a way to avoid transplant shock through the use of a biodegradable containers. U.S. Pat. No. 2,728,169 to Spengler (1955) discloses an improved plant pot made of peat moss fibers reinforced with cellulose, designed to be sturdy enough to withstand commercial handling and yet able to permit unhampered growth of plant roots therethrough. This was intended to permit gardeners to place the plant directly into the soil without removing the peat pot, thus reducing transplantation shock.
Peat pots have numerous disadvantages. As Nancy Bubel writes in "A Place to Germinate" (Horticulture, February 1995, p. 30), "Pots made of pressed peat are advertised as biodegradable, which they are. But my experience is that roots can have trouble penetrating the fiber, especially if the rim is allowed to project above the soil when the pot is put into the garden. Peat pots last only one season and thus their relatively high cost cannot be amortized over a few years. And if you don't store unused pots carefully from one season to the next, they become misshapen and hard to separate. I haven't used them for years."
Eight gardeners used peat pots and plastic pots for germination in tests for National Gardening (January-February, 1994, pp. 50-51). They found "dramatic variations in both growth and yield" between peat pots and plastic containers. Under water-deficit conditions, peat pots compete with the seedling for water and thus deprive the plant of necessary nutrients and moisture. "The poor performance of the peat-pot group could be due to peat pots' tendency to dry out quickly," according to Robert Dufault, vegetable transplant specialist at Clemson University's Coastal Research and Education Center in Charleston, S.C.
Numerous efforts have been made to find practical biodegradable alternatives to the peat pot. Cigarette papers used for commercial sleeves have too little wet strength. Teabag papers and coffee filters decompose too quickly. It is conventional wisdom among those familiar with the art of home gardening that paper products are unsatisfactory for this purpose. It is widely believed that ordinary paper will fall apart too soon and thus not be suitable for germination and growth, while more expensive cardstocks or cardboard will inhibit root growth.
Numerous non-biodegradable containers for seed germination are in common use. Plastic, pressed fiber, and wood are used as containers for germination. The major disadvantage of all such containers is that they require transplantation of the seedlings, resulting in transplant shock. While some offer clear plastic covers to reduce water loss, none offers a complete ready-to-grow system designed to be used by novice gardeners. Amateur gardeners will, as a result, suffer plant losses from improper selection of materials and/or management of the growing regime.
Soil blocks, made by molding wet soil using a special tool, can be introduced directly into the garden without transplantation. They have several disadvantages, however. Special soil mixtures, which may not provide optimum germination and growth, must be used to mold the blocks. Directly watering soil blocks is likely to cause them to disintegrate, so they must be placed on a special watering mat. The large exposed surface area causes them to dry out quickly, affecting the seedlings access to water. Roots are pruned by exposure to air, restricting development of the root system. Because soil blocks lack external support, they may collapse if tilted or jarred when moved. Considerable care is required to avoid complete loss of the plant due to crumbling of the soil block. The blocks are thus not well suited to use by amateur gardeners and are not an integral part of a workable system for managing germination and growth of seedlings prior to their introduction into the home garden.
U.S. Pat. No. 4,881,344 to Frey (1989) describes a tubular sleeve for plant germination substrate consisting of a polymer mass and nonwoven, bonded fiber material treated with fungicides, in which cellulose fibers predominate. The described invention is intended to overcome difficulties in high-speed methods of plant germination for commercial operations. The disadvantage of such a biodegradable sleeve is that it requires very large specialized production runs of a custom material. This material is not currently available in the U.S.